Potash Corp of Saskatchewan's best hope of escaping BHP Billiton's $39bn (£25bn) hostile takeover bid has received a blow from a local government minister.

The Saskatchewan government says it is unlikely to support a takeover of the Saskatoon-based fertiliser company by a sovereign wealth fund, a state-owned firm from China or any other large potash-buying nation because it fears its primary motive would be to deflate the price of the region's most important asset.

A rival bid from the Chinese had been seen as Potash Corp's best hope of avoiding the clutches of BHP after its mining rivals Vale and Rio Tinto have signalled that they will not be launching a rival bid.

Saskatchewan energy minister Bill Boyd said: "It would seem to us … that their interest and the interest of taxpayers of Saskatchewan may not be aligned."

While the provincial government does not have the final say over any deal, its support is seen as crucial. Boyd has also announced that the Conference Board of Canada will conduct an independent analysis of a proposed takeover. "No matter who owns the potash mines, the people of Saskatchewan own the potash," he said.